Читать книгу The First Book of Farming - C. L. Goodrich - Страница 18

Of what use are roots to plants, or, what work do they perform for the plants?

If the reader has ever tried to pull up weeds or other plants he will agree that one function of the roots of plants is to hold them firmly in place while they are growing.

Experiment.—Pull two plants from the soil, shake them free of earth, and place the roots of one in water and expose the roots of the other to the air. Notice that the plant whose roots are exposed to the air soon wilts, while the one whose roots were placed in water keeps fresh. You have noticed how a potted plant will wilt if the soil in the pot is allowed to become dry (see Fig. 4), or how the leaves of corn and other plants curl up and wither during long periods of dry weather. It is quite evident roots absorb moisture from the soil for the plant.

Experiment.—Plant some seeds in tumblers or in boxes filled with sand and in others filled with good garden soil. Keep them well watered and watch their progress for a few weeks (see Fig. 5). The plants in the garden soil will grow larger than those in the sand. The roots evidently must get food from the soil and those in the good garden soil get more than those in the poorer sand. Another important function of plant roots then is to take food from the soil for the plant.

You know how thick and fleshy the roots of radishes, beets and turnips are. Well, go into the garden and see if you can find a spring radish or an early turnip that has sent up a flower stalk, blossomed and produced seeds. If you are successful, cut the root in two and notice that instead of being hard and fleshy like the young radish or turnip, it has become hollow, or soft and spongy (see Fig. 6). Evidently the hard, fleshy young root was packed with food, which it afterwards gave up to produce flower stalk and seeds.

A fourth use of the root, then, is to store food for the future use of the plant.

Experiment.—Plant a sweet potato or place it with the lower end in a tumbler of water and set it in a warm room. Observe it from day to day as it puts out new shoots bearing leaves and roots (see Fig. 7). Break these off and plant them in soil and you have a number of new plants. If you can get the material, repeat this experiment with roots of horse-radish, raspberry, blackberry or dahlia. From this we see that it is the work of some roots to produce new plants. This function of roots is made use of in propagating or obtaining new plants of the sweet potato, horse-radish, blackberry, raspberry, dahlia and other plants.

FIG. 4.

To show that plant-roots take water from the soil, the plants in A are suffering from thirst. B has sufficient water.ToList

FIG. 5.

To show that plant-roots take food from the soil. Both boxes were planted at the same time.ToList

FIG. 6.

A radish root, from which the stored food has been used to help produce a crop of seeds.

Notice the spindle shaded seed-vessels.ToList

FIG. 7.

A sweet-potato root producing new plants.ToList

We have now learned five important things that roots do for plants, namely:

Roots hold plants firmly in place.

They absorb water from the soil for the plants.

They absorb food from the soil for the plants.

Some roots store food for the future use of the plant.

Some roots produce new plants.

How do the roots do this work? To answer this question it will be necessary to study the habit of growth of the roots of our plants.